Airlock in Pipes? Here’s How to Clear It

Airlock in Pipes? Here’s How to Clear It

An airlock in the pipes will either prevent hot water from leaving the taps or leave your radiators cold.

Airlocks happen when there’s trapped air in the hot water or central heating system, preventing the hot water from circulating properly. In this guide, we’ll take you through the steps to clear the air from the system so that the water can flow normally again.


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What is an airlock?

An airlock happens when air is trapped in the system, which will block the hot water as it makes its way to the taps or the central heating system.

An airlock in the hot water system will prevent water from coming out of the affected tap. While an airlock in the central heating system will result in some, or all, of your radiators failing to heat up properly.

How to clear an airlock from hot water pipes

There are many ways to clear an airlock from the pipes of a hot water system and we’re going to take you through 2 of the simplest methods that you can attempt yourself.

If you find that you’re unsure at any point or don’t feel confident then contact a heating engineer to remove the airlock for you.

Clear trapped air in hot water system: Method 1

The first way to clear an airlock, involves attaching a hose pipe to the hot and cold taps at a sink in your home and turning the cold tap on so that the water flows through the hose pipe, into the hot water tap, removing the air.

What you’ll need:

  • 1 metre of garden hose pipe
  • Duct tape

Step 1: Turn your hot water supply on.

Step 2: At 1 of the sinks in your home, use the hose pipe and duct tape to connect the hot water tap outlet with the outlet of the cold water tap. Put the open ends of the hose pipe where the water comes out and duct tape them in place, making sure it’s secure.

Step 3: Turn the hot water tap on.

Step 4: Turn the cold water tap on for 3-5 seconds and then turn it off.

Step 5: Run the hot water at a sink in another room.

Step 6: Repeat the process 5-8 times.

If the hot water is working, you’ve successfully cleared the airlock. If not, then you might want to try the second method.


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Clear trapped air in hot water system: Method

In the case that using a hose pipe to clear the trapped air in your hot water system hasn’t done the trick, there are some alternative steps you can follow.

Step 1: Turn off the mains water supply.

Step 2: Turn on all taps, beginning with the top floor and then working your way downstairs, and wait until the water stops flowing.

Step 3: Flush all toilets until no water is left too.

Step 4: Turn your taps until they’re almost completely off so that a small amount of water will be able to get through.

Step 5: Turn the water supply back on.

Step 6: Turn all taps until their halfway open and then open them up all the way.

Following these steps should force any trapped air out of the system, allowing the hot water to flow again.

Should neither of the above methods work, then it’s time to contact a professional heating engineer.

How to clear an airlock from the central heating system

You’ll know if there’s air trapped in your heating system because 1 or more of the radiators around your home will either only heat up at the bottom or fail to heat up at all. This is because the air is acting as a blockage, stopping the hot water from circulating.

Clearing this trapped air is simply a case of bleeding the radiators, which you can find out how to do in our guide to bleeding a radiator.

Get free repair quotes

If you’ve tried clearing the airlock by following all of the steps above but still aren’t getting any hot water, then it’s time to contact a heating engineer.

A heating engineer will start by finding out that an airlock is actually causing the problem and then, if it is, clear the trapped air from the system.

You can get free no-obligation repair quotes from up to 3 Boiler Guide Approved Heating Engineers based in your local area by completing our simple online form. Comparing multiple quotes will give you the highest chance of finding the best deal for the work.


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Get FREE quotes from heating engineers near you.